1. The Field of the Invention
The present invention relates to a hoisting and lowering driving engagement multi-row chain. More particularly, the present invention relates to a hoisting and lowering driving engagement multi-row chain which is incorporated into a hoisting and lowering device, which hoists and lowers a hoisting and lowering table in parallel with a set surface. Such hoisting and lowering devices may be used as production facilities in various kinds of production fields, transfer facilities in the transportation field, care facilities in the medical welfare field, stage facilities in the art field, and the like.
2. The Relevant Technology
One example of a hoisting and lowering device is a so called chuck chain, which hoists and lowers articles, such as heavy articles, using an engagement chain, which is integrally formed with the table T, which is used to lift and lower the articles, such as the chain described in Japanese Patent Publication No. JP-3370928, which is shown in FIG. 1.
As shown in FIG. 8, one example of such an engagement chain, is a multi-row engagement chain 500 in which a plurality of inner link units 530 each comprising a pair of right and left inner plates 510 and a pair of front and rear bushes 520, which are press-fitted into the inner plates 510. The inner plates and rear bushes 520 are arranged through intermediate plates 540 in a chain width direction.
In such a multi-row engagement chain 500, inner plates 510, intermediate plates 540 and outer plates 550 are generally formed using a blanking process using the same blanking material with the same shaped metal mold in the same direction so as to enhance production efficiency. The inner plate 510, intermediate plate 540 and outer plate 550 are formed so as to have flat surface-shaped sheared surface cross-sections X at rear portions in the blanking direction, while having rough surface-shaped sheared surface cross-sections Y at front portions in the blanking direction.
As shown in FIG. 8, inner plates 510, intermediate plates 540 and outer plates 550 are respectively arranged with hook portions which are directed toward the same longitudinal direction of the plate and extended toward the same height direction of the plate. As the result, as shown in FIG. 9, each of the shear planes X and break surfaces Y in the respective plates in a plate thickness direction are aligned. One problem with this alignment, however, is that a weight bias is generated over the length of the entire chain due to a weight difference generated between the break surface side Y, which has a relatively lighter weight, and the shear plane side X, which has a relatively heavier weight. This unequal distribution of weight is made more burdensome when the weight of articles to be hoisted and lowered in the chain width direction are added, often resulting in drive noise and shortened chain life.
Further, when the engagement chain 500 is particularly lengthened in the longitudinal direction of the chain so that the hoisting height of the articles to be hoisted and lowered is set higher, the engagement chain 500 may twist in a fixed direction while the chain is hoisted, in accordance with the above-described deterioration of the load balance of the engagement chain 500. This results in additional problems, as the inner plates 510, intermediate plates 540, and outer plates 550 in a pair of engagement chains 500 become disengaged and buckle.
Accordingly, the purpose of the present invention is to solve at least some of these problems, that is the object of the present invention is to provide a hoisting and lowering driving engagement multi-row chain in which the weight balance of the whole chain over the chain width direction is controlled so as to improve the load balance with respect to the weight of articles to be hoisted and lowered and the like, so that the articles to be hoisted and lowered may be stably hoisted at higher positions. Thus, a purpose of the present invention is an improvement of endurance of the chain, a reduction of driving noise and miniaturization of the chain size while suppressing the biasing or deflecting of intermediate tooth plates and inner tooth plates.
The subject matter claimed herein is not limited to embodiments that solve any disadvantages or that operate only in environments such as those described above. Rather, this background is only provided to illustrate one exemplary technology area where some embodiments described herein may be practiced.